The U.S. Defense Department is asking armed citizens not to stand guard at military recruiting offices.

Following attacks on military recruiting centers in Chattanooga, Tennessee, that killed five servicemen, Americans have been flocking to recruiting stations around the country to protect military personnel.

“While we greatly appreciate the outpouring of support for our recruiters from the American public, we ask that individuals not stand guard at recruiting offices,” Pentagon press secretary Peter Cook wrote in a statement, adding that the practice “could adversely impact our mission and potentially create unintended security risks.”

The statement followed an incident at a military recruiting center in Lancaster, Ohio, in which a volunteer guard accidentally discharged his rifle.

The Columbus Dispatch newspaper reported Friday that armed volunteers had been standing guard at the River Valley Mall for four days before they were asked to leave hours after the rifle was discharged on Thursday.

Last week, a 24-year-old gunman opened fire at two military facilities in Tennessee, killing four U.S. Marines and a sailor. The shooting renewed debate over military rules that say members of the military cannot be armed on U.S. soil.

But Cook said the military would rely on first responders “for the safety of the communities where our service members live and work."

He said, “Secretary of Defense Ash Carter is currently reviewing recommendations from the services for making our installations and facilities safer — including our recruiting stations."

Cook added, “We take the safety of our service members, our DoD civilians, and the families who support them very seriously.”